Operate and maintain a cell culture laboratory to conduct in vitro assays primarily on materials from natural sources and additionally on selected synthetic materials. Cultivate cells for stock lines and testing. Evaluate and record test results and report these results to NCI. Carry out testing of materials in accordance with protocols and procedures established by NCI. Conduct non-protocol testing related to specific questions which may arise during evaluation of new drugs. Conduct methodological research up to 10% of overall in vitro screening effort.